Assistant Engineer Mechanical

40+ Assistant Engineer Mechanical Interview Questions and Answers

Updated 19 Nov 2024

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Q1. How many types of vibration and their observations or types?

Ans.

There are two types of vibration - free and forced. Free vibration occurs when a system oscillates on its own, while forced vibration occurs when an external force is applied to the system.

  • Free vibration occurs when a system is disturbed and then allowed to oscillate on its own without any external force acting on it.

  • Forced vibration occurs when an external force is applied to a system, causing it to vibrate at a specific frequency.

  • Free vibration can be observed in a simple p...read more

Q2. What is difference between open and close circuit?

Ans.

Open circuit has a break in the circuit, while closed circuit has a complete path for current flow.

  • Open circuit has a switch that is turned off or a broken wire, which prevents current flow.

  • Closed circuit has a switch that is turned on or a complete path for current flow.

  • Open circuit does not allow electricity to flow, while closed circuit allows electricity to flow.

  • Examples of open circuit include a light switch turned off or a broken wire in a circuit.

  • Examples of closed cir...read more

Q3. What is surging and choking in centrifugal compressor?

Ans.

Surging and choking are two common operating conditions in centrifugal compressors.

  • Surging occurs when the flow rate through the compressor is reduced to the point where the compressor cannot maintain a stable flow and pressure. This leads to a pulsating flow and can cause damage to the compressor.

  • Choking happens when the flow rate through the compressor is increased to the point where the compressor cannot handle the volume of gas being fed into it. This results in a decreas...read more

Q4. Maintenance of ball mill and its accociated equipment?

Ans.

Maintenance of ball mill and its associated equipment involves regular inspection, cleaning, lubrication, and replacement of worn parts.

  • Regularly inspect the ball mill and its associated equipment for any signs of wear or damage

  • Clean the ball mill and its associated equipment regularly to prevent buildup of debris and dirt

  • Lubricate the ball mill and its associated equipment as per the manufacturer's recommendations

  • Replace any worn or damaged parts of the ball mill and its ass...read more

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Q5. Ball mill make total length liner categories and diaphragm slot size

Ans.

The total length of ball mill liners and diaphragm slot size depend on the make and model of the mill.

  • The length of the liners and size of the diaphragm slot can vary depending on the manufacturer and model of the ball mill.

  • The liner categories can include single wave, double wave, or corrugated liner designs.

  • The diaphragm slot size can range from a few millimeters to several centimeters, depending on the size of the mill and the desired particle size.

  • The liner and diaphragm ...read more

Q6. What is stroke length of reciprocating compressor?

Ans.

Stroke length of a reciprocating compressor is the distance the piston travels from top dead center to bottom dead center.

  • Stroke length is an important parameter in determining the displacement volume of the compressor.

  • It is typically measured in inches or millimeters.

  • For example, a reciprocating compressor with a stroke length of 4 inches will have a piston that travels 4 inches up and down within the cylinder.

  • Stroke length affects the compression ratio and efficiency of the...read more

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Q7. Why deaerator is being placed at higher elevation?

Ans.

Deaerator is placed at higher elevation to create a pressure difference for efficient removal of dissolved gases from feedwater.

  • Higher elevation creates a pressure difference which aids in the removal of dissolved gases from feedwater

  • This helps in preventing corrosion in the boiler system

  • It also improves the efficiency of the boiler by reducing the amount of oxygen in the feedwater

Q8. How many Types of boiler ?

Ans.

There are several types of boilers used in various industries and applications.

  • Fire-tube boilers

  • Water-tube boilers

  • Electric boilers

  • Condensing boilers

  • Package boilers

  • Industrial boilers

  • Residential boilers

  • High-pressure boilers

  • Low-pressure boilers

  • Steam boilers

  • Hot water boilers

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Q9. How many Yard conveyor safety device?

Ans.

There are various safety devices used in yard conveyors to prevent accidents and ensure safe operation.

  • Emergency stop buttons

  • Safety interlock switches

  • Safety barriers/guards

  • Warning signs and signals

  • Safety sensors for detecting obstacles or personnel in the conveyor path

Q10. How to alignment of yard conveyor?

Ans.

Alignment of yard conveyor is crucial for smooth operation and efficiency.

  • Ensure all components of the conveyor are properly aligned

  • Use laser alignment tools to check and adjust alignment

  • Regularly inspect and maintain conveyor to prevent misalignment

  • Adjust tension and tracking of belts to ensure proper alignment

  • Consult manufacturer's guidelines for specific alignment procedures

Q11. How many types of bearing use in Rolling Mill ?

Ans.

There are several types of bearings used in rolling mills, including roller bearings, ball bearings, and tapered roller bearings.

  • Roller bearings are commonly used in rolling mills due to their ability to support heavy radial loads.

  • Ball bearings are used for lighter loads and high-speed applications.

  • Tapered roller bearings are used to support both radial and axial loads.

  • Other types of bearings that may be used include cylindrical roller bearings and spherical roller bearings.

Q12. Hehehehe What is the least count of screaw gauge?

Ans.

The least count of screw gauge is the smallest measurement that can be read on the instrument.

  • It is the difference between two consecutive divisions on the scale of the screw gauge

  • It is usually expressed in millimeters or fractions of a millimeter

  • The least count of a screw gauge depends on the number of divisions on the circular scale and the pitch of the screw

  • For example, if a screw gauge has 100 divisions on the circular scale and the pitch of the screw is 0.5 mm, then the ...read more

Q13. Explain various types of pumps with its characteristics curves

Ans.

Various types of pumps with characteristics curves

  • Centrifugal pumps: high flow rates, low pressure, used in HVAC systems

  • Reciprocating pumps: high pressure, low flow rates, used in hydraulic systems

  • Diaphragm pumps: positive displacement, used for metering and dosing applications

  • Gear pumps: used for lubrication systems, constant flow rate

  • Axial flow pumps: high flow rates, low head, used in irrigation systems

Q14. A metal has two or more components in it like copper zinc etc

Ans.

The metal is likely an alloy, which is a mixture of two or more metals.

  • Alloys are created by combining metals to improve their properties.

  • Common alloys include brass (copper and zinc), steel (iron and carbon), and bronze (copper and tin).

  • Alloys can have unique properties such as increased strength, corrosion resistance, and conductivity.

  • Alloys are used in a variety of industries including aerospace, automotive, and construction.

Q15. What are type of rolls used for CSP

Ans.

Various types of rolls are used for CSP, including work rolls, backup rolls, and intermediate rolls.

  • Work rolls are used to deform the metal and reduce its thickness.

  • Backup rolls provide support to the work rolls and help maintain the desired shape of the metal.

  • Intermediate rolls are used in between the work rolls and backup rolls to further control the metal deformation.

  • Other types of rolls used in CSP include pinch rolls, coiler rolls, and deflector rolls.

Q16. What is biomass briquetts and pellets?

Ans.

Biomass briquettes and pellets are compressed forms of organic waste used as fuel.

  • Biomass briquettes and pellets are made from organic waste materials such as sawdust, agricultural waste, and forestry residues.

  • They are compressed under high pressure to form dense and uniform fuel sources.

  • Biomass briquettes and pellets are a renewable and sustainable alternative to fossil fuels.

  • They are commonly used in heating systems, power plants, and cooking stoves.

  • Examples of biomass briq...read more

Q17. What are the Safety of chiller?

Ans.

Safety of chiller includes proper installation, regular maintenance, and following safety protocols.

  • Proper installation to prevent leaks and malfunctions

  • Regular maintenance to ensure efficient and safe operation

  • Following safety protocols such as wearing appropriate PPE and avoiding contact with hot surfaces

  • Ensuring proper ventilation to prevent overheating

Q18. Laws of thermodynamics entropy and enthalpy ?

Ans.

Thermodynamics laws governing energy transfer and transformation.

  • First law: Energy cannot be created or destroyed, only transferred or transformed.

  • Second law: Entropy of a closed system always increases over time.

  • Third law: As temperature approaches absolute zero, entropy approaches a minimum.

  • Enthalpy is the heat content of a system at constant pressure.

  • Entropy is a measure of the disorder or randomness of a system.

  • Enthalpy change can be calculated using the formula: ΔH = ΔU ...read more

Q19. What is approach of cooling tower.

Ans.

Cooling towers are heat rejection devices that use water to transfer heat from a system into the atmosphere.

  • Cooling towers work on the principle of evaporation to remove heat from the water being circulated through the tower.

  • The hot water is pumped to the top of the tower and distributed over the fill or packing, where it is exposed to air.

  • As the water flows over the fill, some of it evaporates, which removes heat from the remaining water.

  • The cooled water is then collected at...read more

Q20. What is range of cooling tower.

Ans.

The range of a cooling tower typically varies based on the size and capacity of the unit.

  • The range of a cooling tower can vary from small residential units to large industrial units.

  • Smaller cooling towers may have a range of a few tons of cooling capacity, while larger industrial cooling towers can have a range of hundreds or even thousands of tons.

  • The range of a cooling tower is typically measured in terms of cooling capacity, which is the amount of heat that can be removed ...read more

Q21. what type of actio required for grinding

Ans.

The type of action required for grinding is abrasive action.

  • Grinding involves removing material from a workpiece using an abrasive wheel or belt.

  • The abrasive particles on the wheel or belt create friction and wear away the material.

  • The type of abrasive used depends on the material being ground and the desired finish.

  • Common abrasives include aluminum oxide, silicon carbide, and diamond.

  • The grinding process can be used for shaping, finishing, or sharpening tools and parts.

Q22. What is PTW? How to work?

Ans.

PTW stands for Permit to Work. It is a formal written system used to control certain types of work that are identified as potentially hazardous.

  • PTW is used to ensure that work is carried out safely and in accordance with established procedures.

  • It involves a formal written authorization before starting work in potentially hazardous areas.

  • PTW is commonly used in industries such as construction, oil and gas, and manufacturing.

  • Examples of work that may require a PTW include hot w...read more

Q23. Tell me about piston ring why they use

Ans.

Piston rings are used in engines to seal the gap between the piston and cylinder wall, preventing leakage of combustion gases and oil.

  • Piston rings create a seal between the piston and cylinder wall to prevent leakage of combustion gases and oil

  • They help maintain compression within the combustion chamber

  • Piston rings also aid in heat transfer from the piston to the cylinder wall

  • They reduce friction between the piston and cylinder wall, improving engine efficiency

Q24. Which oil use in gear box ?

Ans.

The type of oil used in a gear box depends on the specific requirements of the gearbox and manufacturer recommendations.

  • The type of oil used in a gear box should meet the manufacturer's specifications.

  • Common types of oils used in gear boxes include mineral oil, synthetic oil, and semi-synthetic oil.

  • The viscosity of the oil is also an important factor to consider when choosing the right oil for a gear box.

  • Regular maintenance and oil changes are essential to ensure the proper f...read more

Q25. Any knowledge about pulley and motors?

Ans.

Yes, I have knowledge about pulleys and motors.

  • Pulleys are simple machines that use a wheel and a rope to change the direction or magnitude of a force.

  • Motors are devices that convert electrical energy into mechanical energy.

  • Pulleys and motors are often used together in mechanical systems to transmit power and motion.

  • Examples of pulley and motor systems include conveyor belts, cranes, and elevators.

Q26. What you know about alloys metals

Ans.

Alloy metals are a combination of two or more metals, resulting in improved properties such as strength and corrosion resistance.

  • Alloys are created by melting and mixing two or more metals together.

  • The resulting alloy has improved properties compared to the individual metals.

  • Common alloys include brass (copper and zinc), bronze (copper and tin), and steel (iron and carbon).

  • Alloys can also be created by adding non-metallic elements, such as silicon or boron.

  • Alloys are used in ...read more

Q27. Types of conveyor belt, working, use.

Ans.

Conveyor belts are used to transport materials. There are different types of conveyor belts for different purposes.

  • Belt Conveyors: used for moving materials horizontally and vertically

  • Roller Conveyors: used for moving heavy materials

  • Slat Conveyors: used for moving irregularly shaped materials

  • Bucket Conveyors: used for moving materials in bulk

  • Magnetic Conveyors: used for moving magnetic materials

  • Vibrating Conveyors: used for moving materials using vibrations

Q28. working principal of ball mill

Ans.

Ball mill is a grinding machine used to grind and blend materials for use in mineral processing.

  • The cylindrical shell rotates around a horizontal axis.

  • The grinding media (balls) are made of steel or ceramic.

  • The material to be ground is fed into the shell through a hollow trunnion.

  • The material is crushed and ground by the impact and friction of the balls.

  • The finished product is discharged through a discharge grate.

  • Ball mills are commonly used in the mining industry and in the ...read more

Q29. Which materials are we using?

Ans.

Various materials are used in mechanical engineering, including metals, plastics, ceramics, and composites.

  • Metals such as steel, aluminum, and titanium are commonly used for their strength and durability

  • Plastics like nylon and PVC are used for their lightweight and corrosion resistance

  • Ceramics such as silicon carbide and alumina are used for high-temperature applications

  • Composites like carbon fiber reinforced polymers offer a combination of strength and light weight

Q30. How many types of compressor?

Ans.

There are two main types of compressors: positive displacement compressors and dynamic compressors.

  • Positive displacement compressors: Reciprocating, rotary screw, rotary vane

  • Dynamic compressors: Centrifugal, axial flow

Q31. What's the superheating?

Ans.

Superheating is the process of heating a substance above its boiling point without it changing into a gas.

  • Superheating occurs in steam boilers when steam is heated beyond its saturation temperature.

  • It increases the energy content of the steam and improves efficiency in power generation.

  • Superheating is important in industrial processes where precise temperature control is required.

Q32. P-V ,T--S diagram otto dual diesel

Ans.

P-V and T-S diagrams are used to analyze the thermodynamic processes in Otto and Diesel engines.

  • P-V diagram shows the pressure-volume relationship during the engine cycle.

  • T-S diagram shows the temperature-entropy relationship during the engine cycle.

  • Otto cycle is used in gasoline engines while Diesel cycle is used in diesel engines.

  • Both cycles consist of four processes: intake, compression, power, and exhaust.

  • The efficiency of the cycles can be analyzed using these diagrams.

Q33. What is LP dosing?

Ans.

LP dosing refers to the process of injecting a low pressure chemical solution into a system or process.

  • LP dosing is commonly used in water treatment plants to add chemicals such as chlorine or coagulants to the water supply.

  • It is also used in industrial processes to introduce additives or inhibitors into pipelines or equipment.

  • LP dosing systems typically consist of a pump, piping, and injection point where the chemical is introduced into the system.

  • The dosing rate is carefull...read more

Q34. How does a VFD work?

Ans.

A VFD (Variable Frequency Drive) controls the speed of an AC motor by varying the frequency and voltage of the power supplied to the motor.

  • VFD converts fixed frequency AC power to variable frequency AC power

  • It adjusts the motor speed by changing the frequency of the electrical power supplied to the motor

  • VFDs are commonly used in HVAC systems, pumps, conveyors, and other industrial applications

Q35. What is machine ?

Ans.

A machine is a device that uses energy to perform a specific task or function.

  • Machines can be powered by electricity, fuel, or human effort.

  • Examples of machines include cars, computers, and washing machines.

  • Machines can be simple or complex, depending on their intended use and function.

  • Machines have revolutionized the way we live and work, making tasks easier and more efficient.

Q36. Explain maintenance process of furnace.

Ans.

Maintenance process of furnace involves regular inspection, cleaning, and repair to ensure optimal performance and safety.

  • Regularly inspecting the furnace for any signs of wear and tear

  • Cleaning the furnace components such as burners, filters, and ducts to remove debris and improve efficiency

  • Replacing any faulty or worn-out parts to prevent breakdowns and ensure safety

  • Checking and adjusting the fuel and air mixture for proper combustion

  • Testing the furnace's performance and eff...read more

Q37. Explain refrigeration cycle.

Ans.

Refrigeration cycle is a process in which refrigerant absorbs heat from a low-temperature space and rejects it in a high-temperature space.

  • Refrigerant absorbs heat from the low-temperature space (evaporator)

  • Refrigerant is compressed to increase its temperature and pressure

  • High-temperature refrigerant releases heat in the condenser

  • Refrigerant expands in the expansion valve to lower its temperature and pressure

  • Cycle repeats to maintain desired temperature in the space

Q38. Comparison ratio diesel engine

Ans.

Comparison ratio in a diesel engine refers to the ratio of the volume of the combustion chamber when the piston is at the bottom of its stroke to the volume when the piston is at the top of its stroke.

  • Comparison ratio is a key factor in determining the efficiency and performance of a diesel engine.

  • Higher compression ratios typically result in better fuel efficiency and power output.

  • Common diesel engine comparison ratios range from 14:1 to 23:1.

  • The comparison ratio is calculat...read more

Q39. What is ferros metal

Ans.

Ferrous metals are metals that contain iron as the main component.

  • Ferrous metals are magnetic and have high tensile strength.

  • Examples of ferrous metals include steel, cast iron, and wrought iron.

  • Ferrous metals are commonly used in construction, manufacturing, and transportation industries.

Q40. Metal has iron components

Ans.

Yes, metal commonly contains iron as a component.

  • Iron is a common component in many types of metal, including steel, cast iron, and wrought iron.

  • Iron gives metal its strength and durability.

  • Other components in metal can include carbon, nickel, and chromium.

  • The specific components and proportions of metal can vary depending on the type and intended use.

  • Metal is used in a wide range of applications, from construction to manufacturing to transportation.

Q41. Types of clutches

Ans.

Clutches are devices used to transmit power from one component to another. There are several types of clutches.

  • Friction clutch

  • Electromagnetic clutch

  • Hydraulic clutch

  • Centrifugal clutch

  • Dog clutch

  • Cone clutch

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